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ISO1050: ISO1050 capacitor selection

Part Number: ISO1050

Hi Team,

My customer is using ISO1050 in their design. They want to know how to choose the capacitor in red box. Do you have any guideline for this?

Regards!

Yangbo

  • Hi Yangbo,

    For these capacitors I would recommend something in the 100pF to 200pF range. You would want to ensure that the bus filtering would not interfere with data transmission, so especially for faster signaling rates, it is critical to not add too much bus capacitance.
    I do not see a part number for the TVS diode that was chosen for the bus. There will be some bus capacitance added by this diode, so take the capacitance of the diode into consideration when choosing the other capacitors.
    As to voltage rating, I would pick at least 50V rated capacitors. The absolute maximum ratings for the bus pins for the ISO1050 are +40V/-27V, so this would put the capacitors outside of that range.

    I hope that answers your question. Please let me know if I can clarify anything or help you further!
    Best regards,
    Dan
  • Hi Dan,

    Thank you very much!
    So the capacitor should be 100pF to 200pF and voltage rating at least 50V. What kind of capacitor do you suggest? Ceramic?
    Do you have any material regarding capacitor that i can share with customer?

    Regards,
    Yangbo
  • Hi Yangbo,

    Ceramic is fine. I don't think we have any material on how to choose that capacitor.  Capacitors are used for this function in the ISO1042DWEVM. You can see that we chose 68pF for that EVM (see page 4). 

    Best regards,

    Dan